Methods and arrangements for automated paint mixing are previously known, among other things through equipment provided by the same applicant. In connection with making holes, it has been previously proposed that the holes should be made by means of a punch device. Arrangements for dosing colour pigment into the tin's base component or base component mixture via the hole that has been made in the tin are also known. For automated paint mixing that works well, it is, however, important that all the functions can be carried out in an optimal way. The proposed punching method is not an optimal way of making holes for all types of tin and all types of material for tins. There is also a desire to be able to make holes in currently available materials for tins such as plastic, cardboard, sheet metal, etc. Concerning the function for dosing of colour pigment, it is important to be able to meet a requirement for more possibilities for colour mixing by means of control functions associated with the utilized microcomputer function.